I hope this is in the right place, I'm not in a hurry, just curious.

How can I find an equation for a line tangent to a point on a parabola without using calculus?

I just started playing with this this morning

The equation I'm using is y = x^2 - 4x - 2 and I'm looking for the equation of the tangent line at point ( 4, -2)

Using calculus I found the equation to be y = 4x -18

How can I do this without calculus?